A 41-year-old German woman was walking along the Elbe’s riverbank in Wedel, Germany, when she came across something that she thought was a piece of amber, the U.K. Telegraph reported.

The woman picked up the stone and put it in her coat pocket. A few minutes later, her coat was on fire. It turns out that the stone wasn’t actually amber — it was white phosphorous.

During World War II, millions of tons of bombs were dropped all over Europe, many of which never actually exploded and remain buried to this day.

Every so often you will read about construction workers finding an unexploded bomb in the middle of a city. However it is much more rare for a random civilian to find a bomb, but apparently it does happen.

The BBC reported that the woman had actually laid her jacket on the beach, so thankfully she wasn’t injured in the blaze.

After this incident, police are warning people to put something that looks like amber in a tin just incase it turns out to be white phosphorous — that way people won’t be horribly burned.

The U.K. Daily Mail reported that white phosphorous is particularly nasty because it cannot be extinguished with water — it must be deprived of oxygen.

White phosphorous can burn right down to bone, causing serious injuries, even death, if not put out right away.

This woman was incredibly lucky that she put her coat down. She could have ended up permanently scarred just from picking up something that looked like amber.

It’s amazing, and sad, that even after all this time bombs dropped during WWII are still all over Europe, and still pose a serious threat to people’s lives.